The present invention relates to a conveyor load spacing mechanism and, more particularly, to a conveyor, whether the loads are light or heavy.
In conventional inclined flow gravity conveyors, loads travel along the conveyor down its incline toward a delivery end where they are removed one by one. In such conveyors, it is advantageous to prevent the entire run of loads positioned along the conveyor from bearing against the lead load at the delivery end of the conveyor so that the lead load can be easily removed from the conveyor. This is particularly desirable where the loads are very heavy such that the successive run of loads which bear against the lead load tend to wedge the lead load tightly against the end stop of the conveyor, thereby making removal of same difficult.
Various load stop and spacing mechanisms have been provided in the past to achieve this load spacing result. One such mechanism is shown in U.S. Pat. No. 3,532,201 issued Oct. 6, 1970 to Kennedy McConnell. In the mechanism shown therein, an actuating lever is connected to a toggle link stop mechanism by rigid rod linkage and these components are mounted adjacent the end of the conveyor. When the lead load is positioned over the actuating lever, it depresses the actuating lever whereby the stop mechanism is extended such that it is positioned in the path of the next successive load to arrest further movement of that load and space that load from the lead load. When the lead load is moved from the end of the conveyor, the actuating lever moves to an extended position and the stop mechanism is retracted to allow the next successive load to move down the conveyor and become the lead load.
In the aforementioned load spacing arrangement it is important that the rod linkage length and the distance between the actuating lever and the stop member be carefully adjusted or selected relative to the length of the loads or the pallets upon which the loads are carried. If the distance is too short, the stop mechanism will be extended too early and move upward toward the stop position before the lead load has cleared the stop mechanism. Since the actuating lever and stop mechanism are rigidly connected together by the linkage, the assembly will likely be sprung and damaged so as to become inoperative where extension is too early.
Conversely, if the distance is too great, the stop mechanism will be extended too late such that it will be extended beneath the next successive load, rather than in front of the load. Such late extensions not only will again result in damage to the rigid linkages, but will likely result in the reaching of two loads to the end of the conveyor at the same time. In order to prevent the latter occurence from happening, that is late extension, a braking mechanism is provided in the McConnell U.S. Pat. No. 3,532,201 for retarding movement of the next successive load temporarily in order to allow additional time for extension of the stop member.
U.S. Pat. No. 3,891,073 issued June 24, 1975 to Coleman and McConnell illustrates a mechanism for spacing successive loads on a conveyor in which the criticality of lengths of the mechanism is minimized and the mechanism itself may be substantially shortened in comparison to the previously described McConnell mechanism. In the Coleman and McConnell mechanism, the stop member may be moved toward its extended stop position even though a lead load has not yet cleared the stop mechanism and the mechanism is thereby positioned in readiness immediately to move into its stop position with respect to the next succeeding load as soon as the lead load has cleared the stop mechanism. The Coleman and McConnell mechanism may be employed for use with pallets of loads having differing lengths and thereby a substantial reduction in mechanism inventory is realized and loads of mixed pallet or load length may be handled simultaneously on a given conveyor without replacement of the mechanism for spacing the loads.
However, both the Coleman, et al patent and the McConnell patent employ toggle mechanisms which require significant spring forces to release same and in fact both patents include over center toggle mechanism in which the loads at the stop mechanism must be moved slightly upstream in order to release the stop mechanism, thereby requiring a great force to be applied against the stop mechanism. The use of heavy springs and the like thereby require rather heavy loads in order to maintain the actuating mechanism in the retracted position thereof. All of this is further required by the fact that both the McConnell patent and the Coleman, et al patent shows mechanisms in which the actuating mechanism is directly linked to the stop mechanism. The springs of both mechanisms have to be adjusted to accommodate heavy or light loads and cannot accommodate both.
Other patents relative to the present invention due to the disclosure of various conveyor braking mechanisms or speed control devices are the Lorden, et al U.S. Pat. No. 3,437,642, the Froio, U.S. Pat. No. 3,700,078, the Froio, U.S. Pat. No. 3,655,021, and the Froio, U.S. Pat. No. 3,312,320, copies of all the foregoing patents mentioned in this section are enclosed herewith.